Blocking all of China

[Hirotaka Fox]

/Also, apparently 70 percent of spam is sent from China by American spam 
outfits who in turn have hosting arrangements with Chinese ISPs."/

Does anyone have a SpamAssassin related way to block all of China?  I 
read things like this on SpamHaus and just want to block all of China 
from sending my company mail.  We don't have any business dealings in China.

Hirotaka